tools: remove unused using declarations

PR-URL: #28422
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Yongsheng Zhang <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>

Author: danbev

tools/snapshot/snapshot_builder.cc

@@ -10,8 +10,6 @@ namespace node {
 using v8::Context;
 using v8::HandleScope;
 using v8::Isolate;
-using v8::Local;
-using v8::Locker;
 using v8::SnapshotCreator;
 using v8::StartupData;